The returning officer will announce the official results soon. Tenaga Nasional has send some workers to ensure that there are no blackouts at the tallying centre.

8.38pm: Some 150 people including BN supporters and journalists have converged at Kampung Bukit Angkat to await Prime Minister Najib Abdul Razak's arrival while also enjoying the local satay and nasi lemak.

Najib is expected to turn up and greet supporters but it is unclear if there will be any changes to the plan.

8.42pm: Unofficial final results:

PKR - 16,770
BN - 11,401

Majority - 5,369

Its winning majority is reduced by 1,455 votes on lower voter turnout of 72 percent.

At the 13th general election last year, PKR's Lim Chin Cheh won with a 6,824-vote majority. The voter turnout was 88 percent.

Both PKR and BN have increased the percentage of the votes.

PKR

2013 - 19,571/33,749 = 57.99%*

2014 - 16,770/28,171 = 59.53%

Increased by 1.54%

BN

2013 - 12,747/33,749 = 37.77%*

2014 - 11,401/28,171 = 40.47%

Increased by 2.7%

*six-cornered fight. Note: Spoilt votes not factored in

8.30pm: Unofficial results:

PKR: 16,581
BN: 11,242

Majority: 5,339

8.15pm: The atmosphere at the PKR operations headquarters in Sungai Sekamat is filled with party members as they await the unofficial results for the Kajang by-election.

Most of the top party leaders, including PKR president and by-election candidate Wan Azizah Wan Ismail, Selangor Menteri Besar Abdul Khalid Ibrahim, have already departed to the Kajang Municipal Council, the main vote-tallying centre.

PKR strategic director Rafizi Ramli says he is satisfied with the results as the party managed to capture two Malay-majority areas which it lost in the last general election, namely Taman Delima and Sungai Sekamat.

"In terms of percentage, it is a bigger win for us even though our majority has gone down. This is because of the lower turnout," he says.

8.14pm: Police have set up a roadblock about 2km from the entrance of Universiti Kebangsaan Malaysia (UKM) and are checking vehicles carrying PKR flags.

There is also a major jam at the entrance of UKM extending to about 1km after police closed an exit from a roundabout heading towards the counting centre at Kompleks Sukan Bandar Baru Bangi.

Police also urged the public to park their cars by the roadside if they want to walk to Surau Ibnu Sina Section 15, Bandar Baru Bangi where PKR candidate Wan Azizah Wan Ismail will move from there to the counting centre.

8pm: Unofficial results:

PKR: 16,086
BN: 10,407

Majority: 5,679

About 93 percent of the votes have now been counted.

7.42pm: On-the-spot analysis:

Based on preliminary results, even though PKR's majority was reduced, its percentage of total votes increased.

In 2013, PKR bagged 19,571 of the 33,749 votes cast (or 57.99 percent). The results today, up to 7.30pm, showed it garnered 15,055 of 24,683 of votes (or 60.99 percent).

However, BN can also boast the same as its percentage of votes similarly increased compared to 2013 as it is a straight fight in this by-election.

Four other candidates had collectively bagged 4.19 percent of votes in the last general election.

BN's share of votes increased from 37.77 percent to 39.01 percent in this election, based on vote count that is still coming in.

7.40pm: Some 100 MCA members are seen gathering at the party operations centre and listen to updates provided by deputy president Wee Ka Siong.

The atmosphere was quiet, while some are spotted jotting down notes.

MCA president Liow Tiong Lai urges party members not to be disheartened by the outcome as the results show that the party has garnered more Chinese votes in this round.

7:35pm: PKR communications director Fahmi Fadzil says PKR won in Sungai Sekamat and Taman Delima, both Malay-majority areas. In GE13, PKR lost in these two areas.

7.30pm: Unofficial results:

PKR - 15,055
BN - 9,628

Majority - 5,427

About 88 percent of the votes have now been counted. It appears that PKR will retain the seat with a reduced majority of about 1,000 votes.

It won Kajang with a majority of 6,824 votes last year at the 13th general election.

7.14pm: Unofficial results:

PKR - 13,414
BN: 8,226

Majority - 5,188

About 80 percent of the votes have now been counted.

7.10pm: Umno supporters and party workers are waiting eagerly for results of the by-election as party officials tally their vote count at the Hulu Langat Umno headquarters.